1. Field of the Invention
The present invention relates to an elbow cover, and more particularly to an elbow cover for armouring piping for air conditioning or temperature control which is made not of sheet metal but of a plastics material by a method using a plastics forming mould.
2. Description of the Prior Art
In various kinds of pipings for air conditioning and temperature control such as heat insulation, cold insulation and the like, it is widely known to cover the piping by winding a suitable insulating material around the piping and then armouring the outside of the insulating material by fitting a cylindrical cover formed from a plastics sheet.
The cylindrical cover is suitable for being fitted to a straight portion of a piping. However, it cannot be used for armouring a corner portion or elbow of the piping. In view of the foregoing, it has been necessary to fit a plastics elbow cover to the elbow portion of the piping.
A known plastics elbow cover which has been extensively used for this purpose is shown in FIGS. 7 and 8 of the accompanying drawings. It is made of a plastics sheet such as, for example, a vinyl chloride sheet about 0.5 mm in thickness, and is formed into a shape such as that obtained by cutting along the inner side of a right angled piece of piping generally designated by reference character A' in FIG. 7.
As shown in FIG. 8, the so-constructed conventional plastics elbow cover A' is mounted on an elbow of piping 1. This is carried out by fitting a cylindrical cover 4 or the like over an insulating material 3 on the elbow portion 2 of the piping 1. The opposite edges 5 formed by cutting open the inner side of the elbow cover A' are separated from each other to form a gap therebetween to fit the elbow cover on the elbow and the edges are then closed so that they abut against or overlap each other. Thereafter, the two ends 6 of the cover A' are fixed on the piping 1 by means of a tape 7 such as a plastics adhesive tape, a metal film tape, a band tape or the like.
Thus, the operation of fittedly armouring the piping 1 with the conventional elbow cover A' requires the use of the tape 7 in addition to the elbow cover A'. Also, mounting the elbow cover A' on the piping 1 requires the operative to wind the tape 7 at both ends 6 with one hand while securely holding the elbow cover A' on the elbow of the piping 1 with the other hand in order to ensure that the edges 5 securely overlap each other, since the insulating material exhibits elasticity due to its being made of an elastic or resilient material such as felt or the like. This results in the operation being highly troublesome and requiring much labour and time, and the operative is required to be skilled.
A conventional elbow cover of a metal sheet such as a tin plate or the like is made by soldering a plurality of arcuate metal sheets together to form a quarter-spherical cover body and then attaching fan-shaped metal sheets to both sides of the cover body. Thus, the metal sheet elbow cover is quite different from the point of view of material, manufacturing process, and constructin as compared to the plastics elbow cover. Also, the two variants tend to be applied to different objects. More specifically, the metal sheet elbow cover is usually fitted on an elbow formed by putting a cylindrical cover or a metal sheet on an insulating material wound on an elbow portion of piping.